Master Plunger G.T. Water Products, Inc. MP100-3 , Black

I purchased this because it’s exactly the same as the plumbers use

Su funcionalidad es única me agrada porque efectivamente destapa el caño

This plunger is the best I've used, and the non-overflow valve is great feature, but no instructions about it are included. It is even printed on the unit itself, "Automatic Overflow Valve" and "Insert Slowly to Prevent Overflow (on top - see pix). It's not totally automatic though. I took some pics to show how it works, there's a slot cut in the threads of the handle that will bleed air out of the chamber if the handle is not tightened securely. With the handle tightened, there is no air bleed however and you would risk an overflow. They should make that clear. I have one of those new "smart" toilets or whatever they're called, the combo bidet (I got a Moen brand). The outlet at the bottom of the toilet is sort of square and I wondered if this would be soft enough to seal completely at the bottom. It's not super soft and flexible by it's nature so I wasn't sure if it would make a good seal at the base, but it didn't matter, because it moves such a large volume of water. This plunger displaces such a large volume of water that on both the plunging downstroke and the suction on return stroke, that it does an amazing job. With the blockage, smart toilet would flush slowly but it detected a blockage so it shut down and refused to flush until it was cleared. I plunged (up and down - water going both directions in the drain pipe) once, and it improved the flushing, but not to 100%. One more time did the trick and it's totally back to normal. EASY! EFFECTIVE! I love this plunger. Cool color too. I saw in comments that some had issues with it not performing that well and I think maybe the handle was in the "vent" position (not screwed on tightly), so some air bleed may have affected the plunging performance. When I got it I wondered how the "Automatic" valve works and it was obviously the slot in the threads providing the air bleed, and it would be sealed by tightening the handle. I tested that on the floor with a rug as a seal, and that's indeed how it works. It's a great feature, just too bad they don't print some simple instructions. Possibly some people used it in the "vent open" mode. I figure that you could probably just leave the handle 1/2 turn loose and insert slowly into toilet to avoid overflowing due to displacement of the water by air in the plunger as it escapes out the threads, and then just plunge away. It has so much volume when plunging, it would probably work fine even with the "valve" open with vigorous plunging. But if you tighten the handle after inserting the plunger in the water, it seals completely and really plunges away! It moves an amazing amount of water in and out, and cleared things up almost instantly. I wrote up some instructions that might prove helpful if you get one of these. I would definitely recommend this plunger.

Excellent! Worked a like a charm on the first try. We are very happy with this plunger. We didn't experience any unpleasant overflow and mess when using this plunger. You are supposed to turn the handle a quarter of a turn to prevent water and contents overflowing over the top of the toilet bowl. It didn't come with a card of instructions. The instructions are on the actual rim of the bellows. They are a bit hard to see, but you can see them if you look closely. This is a plunger you want to keep handy.

This Master Plunger and it's accordian functionality works ever so much better and faster then the red rubber cup type with the wooden handled ones I grew up with. Definitely not going back to the old ones!